The first items in the Biology E/M test are arranged in sets with common answer choices. These items appear in the core section of the test. Remember, these are not MATCHING challenges — each answer choice can be used once, more than once, or not at all.
The inability of two populations to interbreed after being separated by a barrier for a long period of time
Select an Answer
The correct answer is speciation. Recall that the functional definition of a species is a group of organisms that can interbreed with each other but do not interbreed with others. The inability to interbreed after long separation is a sign that speciation has occurred; the two populations now represent two different species.